You may not have intended this, but that sentence reads as though iFlow is merely making less money than it wold like. The problem's worse than that. iFlow would be losing money with each book sold.
iFlow doesn't have the clout to negotiate contracts with individual major publishers: books are made available through a wholesaler. The wholesaler distributes the publisher's cut, takes its own, and gives iFlow itself a cut of _less than_ 30% of the sale price. Since Apple suddenly wants an entire 30% of the sale price, iFlow would literally be losing money with each transaction to make up Apple's "cut".
As part of the agency model, all books must be sold at the same retail price, so iFlow can't simply bump up the price of its books to compensate, either.